Orthoclase from the Greek for “break straight” belongs to the feldspar family of minerals that literally cover the Earth, which also includes moonstone, amazonite, spectrolite and labradorite. Yellow Orthoclase is a transparent yellow feldspar resembling citrine quartz or yellow beryl and is primarily found in Madagascar. Orthoclase is often colorless or champagne-colored potassium feldspar. Its hardness of 6-6.5 on Mohs scale makes orthoclase suitable for gem collectors and as jewelry in the shape of pendants, earrings and pins.

Crystals are usually opaque, may be translucent or rarely transparent. Luster is vitreous to dull. Some crystals that may show opalescence are called moonstone.

Mostly cut in round and facet cut.

Orthoclase location and deposits
The most important deposits are found in Madagascar. Other locations are found in Kenya and Myanmar.

Common Orthoclase treatments
There are no treatments known that could enhance the quality of orthoclase.

World-famous Orthoclase
Orthoclase is in no position to enter the elite circle of world-famous gemstones.

Orthoclase gemology
Species: Feldspar
Color: Colorless or champagne colored
Chemical composition: KalSi3O8 potassium aluminum silicate
Crystal system: Monoclinic, prismatic
Hardness: 6-6.5 (Mohs scale)
Specific gravity: 2.56 – 2.59
Refractive index: 1.518 – 1.526
Birefringence: -0.008
Color of streak: White,
Absorption spectrum: Not diagnostic
Fluorescence: Weak; bluish, orange

The Orthoclase zodiac, myth & legend
The healing powers of gems remain a controversial issue, but are mentioned for centuries by healers, shamans and medicine men. Whether it’s a fact or a placebo effect doesn’t matter, if it helps. The safest approach is to wear the gemstone in skin contact to the troubled part of the body. Orthoclase is said to be of help at heart ailments.